Surface inspection device and surface inspection method

Abstract

A surface inspection device includes an image generator for generating a digital image achieved by imaging an inner surface of a bore which is subjected to a boring work, a line extraction processor for extracting a line along a horizontal direction set to a line extraction direction from the digital image, for determining the state of the inner surface of the bore based on the line extracted by the line extraction processor. The line extraction processor extracts lines along the line detection direction from respective digital images before and after rotation which are achieved by rotating the digital image once or over plural times every predetermined angle while the line extraction direction is fixed, and the estimating unit determines the state of the inner surface of the bore based on the lines extracted from the respective digital images before and after the rotation.

The invention claimed is:  
     
       1. A surface inspection device comprising:
 image generating means that generates a digital image achieved by imaging a surface of a machined workpiece; 
 line extracting means that extracts a line corresponding to a flaw along a predetermined line detection direction from the digital image; and 
 determining means that determines a surface state of the workpiece on the basis of the line extracted by the line extracting means, wherein the line extracting means rotates the digital image once or over plural times every predetermined angle while the line detection direction is fixed, and extracts lines along the line detection direction from respective digital images before and after the rotation, the determining means determines the surface state of the workpiece on the basis of the lines extracted from the respective digital images before and after the rotation, and the respective digital images before and after the rotation shows a same area on the surface of the machined workpiece. 
 
     
     
       2. The surface inspection device according to  claim 1 , wherein the extracting means rotates the digital image on the basis of an angle of a line intersecting to the line detection direction at the maximum angle among extractable lines having predetermined thicknesses when lines are extracted along the line detection direction. 
     
     
       3. The surface inspection device according to  claim 1 , further comprising binarization processing means that performs binarization processing on the basis of brightness values of the digital image, wherein the line extracting means executes line extraction on the binarized digital image as a target. 
     
     
       4. The surface inspection device according to  claim 1 , further comprising coupling means that couples flaws separated from each other by a fixed amount in the line detection direction out of flaws displayed on the display image, wherein the line extracting means executes the line extraction on a digital image as a target on which the flaws are coupled to each other by the coupling means. 
     
     
       5. A surface inspection method comprising:
 a line extracting step that extracts a line corresponding to a flaw along a predetermined line detection direction from a digital image achieved by imaging a surface of a machined workpiece; and 
 a determining step that determines a surface state of the workpiece on the basis of the line extracted in the line extracting step, wherein in the line extracting step, the digital image is rotated once or over plural times every predetermined angle while the line detection direction is fixed, and lines along the line detection direction are extracted from respective digital images before and after the rotation, in the determining step, the surface state of the workpiece is determined on the basis of the lines extracted from the respective digital images before and after the rotation, and the respective digital images before and after the rotation shows a same area on the surface of the machined workpiece. 
 
     
     
       6. The surface inspection device according to  claim 1 , comprising a combination processor superimposing each of the lines extracted from the respective digital images before and after the rotation on the digital image,
 wherein the combination processor reversely rotates the lines extracted from the digital images after the rotation to superimpose on the digital image. 
 
     
     
       7. The surface inspection device according to  claim 1 , wherein the respective digital images before and after the rotation shows a same part of the surface of the machined workpiece.